Keyless access control device for motor vehicles

ABSTRACT

The invention relates to a keyless access control device for motor vehicles, having a transceiver device assigned to the motor vehicle and a mobile transponder. The aim of the invention is to solve the technical problem of providing an access control device which makes it possible to intentionally unlock individual doors or hatches and efficiently prevents the undesired unlocking of vehicle doors. To this end an actuating element which influences a switch cooperating with a control device is protected against actuation by a movable mechanical cover until reception of a first coded message containing a coarse identification of the authorized user.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation of International ApplicationPCT/EP00/00157, with an international filing date of Jan. 12, 2000.

TECHNICAL FIELD

[0002] The invention pertains to a keyless access control device, inparticular, a keyless access control device for motor vehicles thatcontains a transceiver device assigned to the motor vehicle and a mobiletransponder, where the transceiver device and the transponder exchangecode signals in order to carry out a bidirectional question-and-answerdialogue for checking the access authorization, and where a controldevice is provided that cooperates with at least one electric switchthat is influenced by at least one operating element assigned to themotor vehicle.

BACKGROUND ART

[0003] A method and device of this type are known from the article “EinFahrzeugsicherungssystem ohne mechanischen Schlüssel” [A Motor VehicleSecurity System without Mechanical Key] by Ch. Schneider and U. Schreywhich was published in “Automobiltechnische Zeitschrift 96” (1994), No.5, as well as from the article “Smart-Card—Abschied vom Autoschluissel”[Smart-Card-Farewell to the Car Key] by U. Schrey, Ch. Schneider and M.Siedentrop which was published in “Siemens Zeitschrift 1/96.” The accesscontrol device described in these articles essentially consists of atransceiver device that is assigned to the motor vehicle and a mobiletransponder. The transceiver device comprises three transmitters(LF-transmitters) that operate in the inductive frequency range, whereone transmitter is assigned to the driver-side door, another is assignedto the passenger-side door and a third is assigned to the trunk of themotor vehicle. The transmitting antennas of the LF-transmitters areintegrated into the respective car doors and into the rear bumper. EachLF-transmitter is connected to the door handle assigned to therespective door and to the trunk release button in such a way that whenthe door handle or the trunk release button is actuated, theLF-transmitter assigned to this region of the motor vehicle transmits alow-frequency code signal (LF-signal). The remaining LF-transmittersremain inactive and do not transmit LF-signals.

[0004] The transceiver device assigned to the motor vehicle is alsoequipped with an HF-receiver for receiving an HF-signal from thetransponder. The answer signal of the transponder that is received inthe HF-receiver acts on a control unit that is equipped with aprocessor. The answer signal that was received in the form of anencrypted code is decoded and checked with respect to its validity inthis control unit. If the result of this validity check is positive, acorresponding control signal is delivered to the respective door lockingmechanism in order to unlock the door, the door handle of which waspreviously actuated.

[0005] The transponder consists of a so-called access card with anLF-receiver and a low-power HF-transmitter. The inductive receptionantenna is realized in the form of a frame antenna, and thehigh-frequency transmission antenna is realized in the form of aprinted-circuit board antenna. The LF-signal received by the LF-receiverof the transponder is decoded in the transponder. A microprocessorassigned to the transponder then processes the code word contained inthe LF-signal with a security algorithm and transmits the result to theHF-receiver of the transceiver device assigned to the motor vehicle bymeans of the HF-transmitter.

[0006] The transmission of LF-signals for “awakening” the transponderresults in a limitation of the functional radius due to the rapidlydecreasing magnetic field. Reception of the transmitted LF-signal isonly possible within a functional radius of 1.5-2 m. This is intended toensure that only those transponders actually located within such a closevicinity are awakened by the LF-transmitter. A definitive localizationof the transponder or the person carrying the transponder is effecteddue to the required actuation of a door handle or a trunk release buttonand the limited functional radius.

[0007] Modified door handle and lock mechanisms that make immediateaccess to the automobile possible via the door, the handle of which waspreviously actuated, are used for unlocking the respective motor vehicledoor as rapidly as possible. However, even these mechanisms do not makeit possible to shorten the time required for transmitting the data fromthe LF-transmitter to the transponder. This applies, in particular, ifcomplex encrypted codes must be transmitted on this low-frequency linkbecause this process requires a certain time due to the low datatransmission speed. However, the transmission of the decoded answersignal from the transponder to the HF-receiver only delays the beginningof the door unlocking process insignificantly.

[0008] Another keyless access control device for motor vehicles is knownfrom DE 43 29 697 C2. This device uses a central LF-transmitter fortransmitting the low-frequency code signal. However, the LF-transmitterof this device transmits LF-signals cyclically within certain intervals.The transponder is only awakened and transmits its answer signal whenthe transponder assigned to the motor vehicle is located within thefunctional radius of the LF-transmitter. In this device, actuation of adoor handle or a trunk release button is not required to trigger theunlocking mechanism. Since with this device localization of thetransponder in order to unlock only certain doors is not possible, thisaccess control device is only suitable for motor vehicles with acentrally controlled locking system. In this known access controldevice, a delayed unlocking also occasionally occurs due to thetransmission time of the LF-signal that may have a complex design undercertain circumstances.

[0009] DE 197 28 761 C1 also describes a keyless access control devicethat uses several LF-transmitters. These LF-transmitters are arrangedwithin certain regions of the motor vehicle and each transmits a signalthat differs from those from the other LF-transmitters. The mobiletransponder that contains an LF-receiver and an HF-transceiver device isawakened by the LF-transmitter and subsequently begins aquestion-and-answer dialogue with the transceiver device assigned to themotor vehicle in order to check access authorization. If the result ofthis question-and-answer dialogue is positive, the corresponding motorvehicle door is unlocked.

[0010] The advantage of this keyless access control device is that it isnot necessary to actuate a door handle in order to initiatecommunication between the motor vehicle and the transponder, i.e., nonoticeable delay occurs between the actuation of the door handle and theunlocking of the door. However, this device also has the disadvantagethat the door(s) may be unintentionally unlocked if an authorized useris in the vicinity of the motor vehicle.

SUMMARY OF THE INVENTION

[0011] Based on the initially discussed state of the art, the inventionaims to propose a keyless access control device for motor vehicles, aswell as a method for implementing a keyless access authorization controlfor motor vehicles, which is not only suitable for unlocking individualdoors or hatches, but also effectively prevents the unintentionalunlocking of the motor vehicle doors, where this keyless access controldevice also allows the exchange of complex code signals and answersignals without a noticeable delay in the unlocking process.

[0012] This objective is attained due to the fact that at least one ofthe operating elements is protected from being actuated by a movable,mechanical cover until a first code message that contains a grossidentification of the authorized user is received.

[0013] A first code signal transmitted by the motor vehicle merelyserves for the so-called “awakening” of the transponder when anauthorized user approaches the motor vehicle. The first coded answersignal which is subsequently transmitted from the transceiver device ofthe transponder serves for a preliminary verification of the accessauthorization which is subject to only a relatively low standard ofsecurity and for opening the covers that were previously concealing theoperating elements.

[0014] Only the actuation of one of these operating elements initiatesthe question-and-answer dialogue between the transceiver device assignedto the motor vehicle and the transponder which is carried out with ahigh standard of security.

[0015] System security is significantly increased due to the fact thatthis question-and-answer dialogue only takes place once the user, whowas identified as a presumably authorized user during the initial grossverification, expresses his desire to open the motor vehicle byactuating the door handle. The actions of the user simultaneouslyidentify the door to be opened if another type of unlocking is notdesired (e.g., in accordance with a centrally controlled lockingsystem).

[0016] It is advantageous that the operating elements are formed by thedoor handles of the motor vehicle.

[0017] It is also advantageous that electromotive driving means are usedfor opening and closing the mechanical cover of at least one of theoperating elements.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Additional advantages of the invention are disclosed below withreference to a preferred embodiment. The drawings show:

[0019]FIG. 1, a schematic representation of a keyless access controldevice for motor vehicles, and

[0020]FIGS. 2A and 2B, one option for realizing the mechanical cover ofa door handle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0021]FIG. 1 schematically shows a motor vehicle 1 equipped with akeyless access control device. The access control device consists of acontrol unit 3 arranged in the motor vehicle 1, with a transceiverdevice 2, as well as electric switches 6′, 7′, 8′ that cooperate withthe door handles 6, 7, 8 via corresponding lines, connected to saidcontrol unit. The transceiver device 2 contains at least one transmitter4 and one receiver 5 for carrying out a question-and-answer dialoguewith a mobile transponder 9. The transponder 9 also contains atransmitter and a receiver, as well as a microprocessor for carrying outthe processes associated with the question-and-answer dialogue. Thepower supply of the transponder 9 (not shown in greater detail)comprises a rechargeable battery, e.g., a lithium-ion battery.

[0022] A keyless access authorization control with the access controldevice shown in FIG. 1 is carried out as described below:

[0023] The transmitter 4 transmits a coded signal that is received bythe transponder 9 as it approaches the motor vehicle 1, e.g., whilebeing carried in the pocket of the authorized person, and serves to“awaken” the transponder 9. The transponder 9 recognizes the codedsignal and transmits a coded answer signal.

[0024] The transceiver device 2 which is arranged in the motor vehicle 1is started simultaneously with the cyclical transmission of the codedsignal. The coded answer signal transmitted by the transponder 9 isreceived by the transceiver device 2 in the motor vehicle 1. Thereceived code is checked, and if the results of the check are positive,the electric switches 6′, 7′, 8′, as well as the door handles 6, 7, 8which cooperate with these electric switches, are released by thecontrol unit 3. This release is effected by making the door handles 6,7, 8 accessible to the user, namely by retracting the covers thatpreviously covered the door handles.

[0025]FIGS. 2A and 2B show a possible embodiment of these covers: theoutside of the door 11 contains a handle depression 12 that is initiallyentirely covered by the handle element 13 as shown in FIG. 2A, so thatthe handle element cannot be moved by hand. Once the door handle isreleased, an electric motor moves the handle element 13 upward,resulting in the situation shown in FIG. 2B. Here, the part 13′ of thehandle element 13 which previously covered the handle depression 12partially disappears behind the door 11 and the user is able to actuatethe handle element by hand within the region 12′ of the handledepression. In this position, the handle element 13 can also be raisedby hand such that the electric switch assigned to this handle element isactuated.

[0026] The actuation of the switch causes the bidirectionalquestion-and-answer dialogue between the transponder device 2 in themotor vehicle and the transponder 9 to be initiated. The accessauthorization is checked during this dialogue. The answer signal of thetransponder 9 which is received by the transceiver device 2 is decodedand compared to a nominal value or several nominal values, whereafterthe access authorization of the person carrying the transponder isdetermined. Once a valid answer code signal is received, the controlunit 3 delivers a release signal to the motor vehicle door, the handleelement of which was actuated, in order to unlock this door.

[0027] A transponder receptacle, into which the transponder 9 with itsferrite core antenna 10 can be inserted, is arranged at a suitablelocation in the motor vehicle 1. An inductive charging device isassigned to this transponder receptacle so that the rechargeable batteryof the transponder 9 is recharged when the motor vehicle 1 is in use. Anadditional device for carrying out question-and-answer dialogues is alsoassigned to the transponder receptacle. These question-and-answerdialogues are carried out analogously to the previously describedquestion-and-answer dialogue, but with the objective of switching off atransmission lock and/or inquiring or starting other security oroperating conditions.

What is claimed is:
 1. A keyless access control device for a vehiclehaving a door and a door handle, the device comprising: a coverassociated with the door handle, wherein the cover is movable between afirst state in which the cover covers the door handle to preventactuation by a vehicle user and a second state in which the coveruncovers the door handle to allow actuation by the vehicle user; acontroller associated with the vehicle, the controller operable formoving the cover between the first and second states; a transceiverassociated with the vehicle, the transceiver operable for transmitting acode signal and for receiving an answer signal; and a transponderassociated with the vehicle user, the transponder operable for receivingthe code signal from the transceiver and for transmitting an answersignal to the transceiver in response to receiving the code signal;wherein the transceiver checks the answer signal received from thetransponder to conduct a preliminary verification of whether the vehicleuser is authorized to access the vehicle; wherein the controller movesthe cover from the first state to the second state to uncover the doorhandle to allow actuation by the vehicle user if the preliminaryverification is indicative of the vehicle user being authorized toaccess the vehicle.
 2. The device of claim 1 wherein: the controller isfurther operable for locking and unlocking the door, wherein uponactuation of the door handle by the vehicle user the transceiver andtransponder conduct a bidirectional question and answer dialog toconduct a final verification of whether the vehicle user is authorizedto access the vehicle, wherein the controller unlocks the door if thefinal verification is indicative of the vehicle user being authorized toaccess the vehicle.
 3. The device of claim 1 wherein: the cover isformed by a handle element of the door handle, wherein in the firststate of the cover the handle element is prevented from being actuatedby the vehicle user and in the second state of the cover the handleelement is enabled to be actuated by the vehicle user.
 4. The device ofclaim 1 wherein: the controller includes electromotive driving meansoperable for moving the cover between the first and second states.